1. Field of the Invention
The present invention generally pertains to a launder for discharging melt from a metallurgical furnace and a metallurgical furnace installation using the same launder. In particular, the present invention relates to an improvement in the structure of the portion at which the melt passageway is temporarily closed by casting a closing material such as a lump of castable thereon.
2. Conventional Art
FIG. 5 is a schematic cross-sectional view of a conventional melt discharging launder 1 connected to a converting furnace 2 for producing blister copper. In this known arrangement, the converting furnace 2 is constructed to have a circular furnace body 2a and a siphon type outlet 2b formed integrally therewith so as to be communicated with the furnace body 2a. The conventional melt-discharging launder 1 is connected at one end to outlet 2b, while its other end is connected to an anode furnace (not shown). Thus, melt 3, i.e., blister copper melt, which is contained in the furnace body 2a, is caused to overflow or siphoned out from the top of the outlet 2b into the launder 1 when the melt level in the furnace body 2a exceeds the level of the launder 1, and slag 4 floating on the melt 3 in the furnace body 2a is prevented from being discharged.
In the aforesaid type of melt discharging launder 1, the portion in the immediate vicinity of the top of outlet 2b defines a threshold portion 5 for determining the melt level in furnace 2 above which the melt 3 in the furnace begins to overflow into the launder 1. In addition, when it is necessary to temporarily close the melt passageway of the launder 1, a prescribed quantity of castable 6 or refractory material is casted on the above threshold portion 5 to dam up the melt. The castable 6 thus casted should subsequently be removed in order to permit the flow of the melt once again.
However, it has been very difficult to completely remove the castable on the threshold portion 5 because the castable 6 adheres to a bottom 5a thereof. As a result, the castable 6 gradually accumulates, thereby raising bottom 5a, such that melt level in the furnace 2, above which the melt in the furnace begins to overflow into the launder, will ultimately vary.
Moreover, inasmuch as the threshold portion 5 is arranged adjacent to the outlet 2b, the casting operations of the castable 6, which are performed mainly by human labor, are conducted in extremely hot environments caused by the emission of radiant heat from the melt 3, thereby rendering the operators with an excessive physical burden.